The performance of a hearing aid depends, among other things, upon the design of the microphone pickup. The microphone is a substantial part of the hearing aid. Further, where a hearing aid uses a circuit board which requires electrical connections to be completed during the hearing aid assembly, the ease and simplicity with which the electrical connections can be made impacts the cost of manufacture. Hearing aids which can be manufactured at relatively lower cost are desirable, since they can be disposed of after use.
Examples of the use of hearing aid microphones or transducers are known in published literature.
U.S. Pat. No. 5,388,163 to Elko et al. teaches an electret foil transducer array comprising an electret foil having a layer of insulating material and a layer of metal in contact therewith. The transducer portion of the array comprises one or more discrete areas of foil with the surrounding areas removed. Alternatively, the discrete areas of foil could be formed by selective metal deposition. Electrical leads are coupled to the discrete areas of metal. By means of the electrical leads, electrical signals produced by each transducer in response to acoustic signals which become incident in use on the areas of foil are used for further processing. The electret foil is made up of the discrete areas of foil with a backing of polytetrafluoroethylene PTF or, alternatively, Mylar®. The electret foil is backed by a porous backplate (e.g., of sintered aluminum) with a rough surface to provide air channels. The porous backplate may be supported by a uniformly supporting metal screen to provide increased rigidity.
Nevertheless, despite such prior art, a need exists for a hearing aid with a relatively large diaphragm and improved low noise microphone characteristics performing with high efficiency, which is capable of being manufactured at low cost and economy, thereby facilitating the manufacture of hearing aids which are sufficiently inexpensive so that they can be disposed of after short periods of use. Additionally, there is a need for a hearing aid wherein electrical connections, which need to be made during manufacture, can be completed in a simple and economical manner and in a less labor intensive and effective process.